Bit-stock



(No Model.)

Q. S. BACKUS. Bit Stock,

No. 234,517. Patented Nov. 16, |880.

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QUIMBY S. BACKUS, OF W'INCHENDON, MASSACHUSETTS.

BIT-STOCK.

SPECIFICATION forming part of Letters Patent No. 234,517, dated November 16, 1880.

Application filed September 29, 1880.

such as will enable others skilled in the art to which it appertains to make and use the saine, reference being' had to the accompanying dra-wings, and to the letters or figures of reference marked thereon, which form a part of this specification.

This invention relates to that class of bit-v braces in which the shank of the bit is held byjaws embracing its sides, while its end is received into and steadied by a socket formed in the body or socket-piece of the bit-holder, the object being to so attach the jaws to the socket-piece that while their freedom of movementin a lateral directionis maintained, they will be prevented from moving longitudinally when thebitis withdrawn or atother times; and the invention consists in forming the grooves of the bit-holder in which the jaws are placed with fulcrnm-points, upon which thejaws oscillate, and providin the lower ends of the latter with a nick or projection, which receives a corresponding nick or projection on one end of the springs attached to the socket-piece, and by which the jaws are operated and prevented from moving longitudinally, all as will be hereinafter fully described.

In the accompanying drawings, Figure l shows a section ofthe sleeve, with aside View ofthe socket and one of thejaws. Fig. 2 is a longitudinal section through both sleeve and socket, showing the jaws in the position they assume when closed upon the shank of a bit. Fig. 3 is a side view of the socket, showing the slots within which the jaws are placed, as well as their securing-springs.

The socket A is that part of the device attached to or forming a prolongation of the portion of the brace which forms the handle, and is externally screw-threaded and partially divided into two parts by the diametrical slot B, which divides the socket wholly for a short distance, then branches, forming the extensions tand a', leaving the solid bar or partition be- (No model.)

tween them in which is formed the pyramidal cavity b, for steadying the end of the bitshank.

The bit-holding jaws C are formed of stiff metal bars of the proper width to fit the slots B and aloosely, so as to move easily1 therein, and are slightly curved, so that their outer ends incline toward each other. These ends are provided with cavities (shown by dotted lines in Fig. 2) upon their inner surfaces for the reception of the corners of the bit-shank, their outer surface at the same end being beveled and rounded so as to iit the inner conical bearing-surface of the screw-sleeve D, which incloses the socket and jaws, and by its longitudinal movement causes the jaws to expand or contract, so as to release or seize the bit-shank. Upon the outer surface, near the inner end of the jaws C, is formed a nick,c, which receives hook c', formed upon one end of the plate-springs d, said springs being secured .to the sockets in the narrow and shallow extensions a of the slot B by the rivet or screw c passing through a hole formed in the rounded ends of the springs and a corresponding orrifice piercing the socket at or near the apex of the pyramidal recess b.

lt will be observed that the inner ends ofthe jaws have a tirm bearing in the rounded end of the slots a, thus enabling them to withstand any thrust or blow from the outside without becoming displaced, while the hook c upon one end of the springs d holds them firmly in position against any force which would tend to withdraw them from the socket.

It will also be seen that the points e are the fulcrums upon which the jaws act. As their outer ends are forced inward bythe sleeve D, in the act of grasping a bit-shank, their inner ends expand and bend outward.

The springs d in turn, when the sleeve is so moved as to release the bit by their pressure on the inner ends of the jaws, cause them to rock or oscillate upon the points e, thus expanding their outer ends and releasing the bit-shank.

It will be apparent that the method of securing and operating the jaws above described possesses certain advantages over those bitbraces in which the spring and jaw are formed from the same piece of metal, as in that case the whole must be forged from steel of excellent quality, which is an expensive process, while the jaws used with my brace may be of east metal, and the springs ent from sheets of steel by a die of proper fornl at a single stroke. It also possesses advantages over those bit-braces in which the jaws are connected at their inner ends by a spiral or other spring, as these jaws are always iinperfeetly held in position, being liable to get ont of place whenever lthe least disarran gin g force is applied to them.

Having thus described my invention, I claim as new, and desire to secure by Letters Patent,

J the following:

Witnesses:

FRANK B. SPALTER, Gr. S. LOUD. 

